Conventional industries and high-technology manufacturing processes have strict requirement regarding the quality of the compressed air, that is, dewpoint ≦−70° C., dust size ≦0.1 μm, and oil content ≦0.01 mg/m3. To meet the above quality requirements of the compressed air, the engineering system needs to be equipped with several related equipment such as filtering equipment and cleaning equipment for purifying the compressed air.
According to the conventional drying process of the compressed air, firstly, the compressed air is de-humidified by a refrigerant dryer for reducing the dewpoint to be around 2° C. Then, the compressed air is further processed by an adsorbent dryer for reducing the dewpoint of the air to be between −40˜−70° C. During a dehydration procedure, both the refrigerant dryer and the adsorbent dryer have an air loss. During a cyclic regeneration procedure, the adsorbent dryer has an air loss rate of 5˜20%. Moreover, the existing specification of operating pressure is set to be between 7˜10 kg/cm2, and the energy consumption of the dryer is proportional to the operating pressure. That is, the higher the operating pressure, the worse the energy consumption. To summarize, once the air loss and energy conversion efficiency are resolved during the drying procedure of the compressed air, energy consumption will be reduced. Therefore, it is essential to reduce unnecessary energy loss during the drying procedure of the compressed air.